You are in walking on the city of Fubuki. As you're walking around the streets of the city, you heard some screams of terror, and you rushed to help. Unfortunately, you just saw a serial killer named Ryuunosuke Uryuu had just murdered an entire family for some ritual. The serial killer tries to kill you, but the ritual circle suddenly glows, and you gain a strange red mark on right hand. Suddenly, a figure flashed before your eyes. They said their names was... (Enter Servant Class name).